1. Field of the Invention
The present invention relates to an information recording apparatus for recording an information signal on an information record medium of a recordable type such as a phase change type optical disk, and an information reproducing apparatus for reproducing the information signal from the information record medium.
2. Description of the Related Art
Typically, an optical disk of a read only type has a main record area and sub record areas. A main information signal indicative of main information, such as video information or music information, is recorded on the main record area. The sub record areas are respectively disposed on an inner circumference side and an outer circumference side so as to sandwich the main record area between them. Usually, the sub record area located on the inner circumference side of the main record area is referred to as a lead-in area, and the sub record area located on the outer circumference side of the main record area is referred to as a lead-out area. For example, as shown in FIG. 1, in a case of a DVD (Digital Versatile Disk) 200, an area between a diameter of 48 mm and a diameter of 116 mm is a main record area 201, an area between a diameter of 46 mm and a diameter of 48 mm is a lead-in area 202, and an area between a diameter of 116 mm and a diameter of 117 mm is a lead-out area 203.
The lead-in area 202 and the lead-out area 203 are formed in order to optimally read in the main information signal recorded between the innermost circumference track and the outermost circumference track of the main record area 201.
If it is temporarily assumed that the lead-in area and the lead-out area are not present in the read only type optical disk, there may be a possibility of an occurrence of an event described below. When the main information signal recorded on the innermost circumference track or the outermost circumference track is read in, the movement of a pickup is limited in such a way that the pickup moves towards the innermost circumference track or the outermost circumference track. At this time, if a disturbance occurs, the movement of the pickup may be not correctly controlled. Thus, the pickup may pass the innermost circumference track and move further to the inner circumference side or pass the outermost circumference track and move further to the outer circumference side. Information tracks (pits) are not formed outside the main record area. Hence, if the pickup goes outside of the main record area, it is impossible to obtain the information necessary for the movement control of the pickup (for example, the information to generate a tracking error signal). As a result, the movement control of the pickup can not be done in the worst case.
In order to solve such a problem, the lead-in area 202 is formed further to the inner circumference side of the innermost circumference track in the main record area 201, and the lead-out area 203 is formed further to the outer circumference side of the outermost circumference track in the main record area 201. And, the information tracks (pits) are formed on the lead-in area 202 and the lead-out area 203. Special signals indicative of the lead-in area or the lead-out area are recorded on these information tracks as sub information signals.
Moreover, content information with regard to the main information signal recorded on the main record area, attribute information of the disk and the like are recorded together with the special signals as the sub information signals, depending on the kind of the optical disk.
As for an optical disk of a recordable type, which is referred to as a "recordable optical disk", a record track, a guide track and pre-pits are formed on its recording surface. The guide track is a track for guiding a record light beam to the record track (for example, a groove track), and is referred to as a land track, for example. The pre-pits are pits for recording pre-information to specify positions (addresses) on the disk. When recording information on the recordable optical disk, a recording apparatus can specify the record position of the information by detecting the guide track and the pre-pits and can correctly control the movement of the pickup and the radiation of the light beam.
The recordable optical disk also has areas corresponding to the lead-in area and the lead-out area of the read only type optical disk. The guide track and the pre-pits are also formed in these areas. When recording the information on the recordable optical disk, the recording apparatus records the above-mentioned special signals (if necessary, the content information and the attribute information) on these areas corresponding to the lead-in area and the lead-out area. Accordingly, the recordable optical disk after the information is recorded thereon and the read only type optical disk are unified in format. Therefore, the information recorded on the recordable optical disk can be reproduced by a reproducing apparatus for reproducing the read only type optical disk.
The area in which the information tracks (pit rows) are formed, namely, the main record area can be recognized by the reproducing apparatus by detecting the special signals recorded on the recordable optical disk. In a case of a reproducing apparatus which employs a manner of generating a tracking error signal based on a phase difference of a light beam reflected by the pit rows, it is necessary that the main record area can be exactly recognized in order to surely carry out the movement control of the pickup. Hence, from the viewpoint of such an aspect, it is important to record the special signals.
In the conventional recording apparatus, when the information is recorded on the recordable optical disk, the main information signal is firstly recorded on the recordable optical disk. After all the main information signals to be recorded are recorded, the special signals (if necessary, the content information and the attribute information) are recorded on the lead-in area and the lead-out area. As a result, in order to record the information on the recordable optical disk, the conventional recording apparatus needs not only the recording process of recording the main record information main but also the recording process of recording the special signals. This results in a problem that it takes a long time to carry out the recording process.